Afghan President Hamid Karzai has told a top Pakistani cleric with ties to militants that key Afghan Taliban leaders are either killed or arrested whenever they show willingness to negotiate with his government.

"President Hamid Karzai told me that certain powers kill and arrest important Afghan (Taliban) personalities whenever they find an opportunity to talk to us (Karzai�s government)," Maulana Samiul Haq, the chief of the Jamiat Ulema-e-Islam-S, said after a one-on-one meeting with Karzai on Saturday.

"The Afghan President also mentioned the arrest and killing of key Taliban leaders in Pakistan," Haq said, adding that Karzai said he loses an opportunity for dialogue when the Afghan Taliban personalities are removed from the scene.

"President Karzai told me that he has sensed a positive change in the approach of Pakistani leaders during his official talks," Haq said.

"However, I told him Pakistani leaders cannot play any role in the Afghan peace and reconciliation unless they change their pro-US policy." Haq quoted Karzai as saying that he was in contact with Taliban and that he holds talks with them 'from time to time'. Karzai did not elaborate on the extent of his contacts with the Taliban," he said.

Karzai met senior religious and political leaders during his visit to Islamabad to attend a trilateral summit with the Presidents of Iran and Pakistan.

He sought their help for peace and reconciliation efforts in war-ravaged Afghanistan.

An Afghan diplomat said Karzai extended his visit by a day and wrapped up his trip on Saturday.

He had earlier scheduled a two-day trip but extended it to complete talks with key Pakistani politicians.

Media reports said an angry and frustrated Karzai confronted Prime Minister Yousuf Raza Gilani's delegation during bilateral talks on Thursday and demanded that they produce Afghan Taliban leaders for talks.

Karzai's language and tone flared to such an extent that Gilani briefly halted the meeting, according to one report.

In an apparent response to Karzai's demands, Foreign Minister Hina Rabbani Khar subsequently said Mullah Mohammad Omar, the supreme commander of the Afghan Taliban, was not in Pakistan and Islamabad could not ensure his participation in peace talks.

Khar said it was 'preposterous' to think that Pakistan could deliver Mullah Omar to the negotiating table.

She contended there was no 'clarity' on the role that Kabul wanted Islamabad to play in the Afghan reconciliation process.

When Mullah Baradar, next in line in the Taliban hierarchy after Mullah Omar, was arrested near Karachi in February 2010, a section of the media claimed he had been involved in talks with the Afghan government.

The Taliban denied the report. The Afghan government and Karzai have in the past sought access to and the repatriation of Mullah Baradar, but the demand is believed to have not been accepted.

The Afghan Taliban recently confirmed for the first time that top leader and former Defence Minister Mullah Obaidullah had died in a Pakistani prison.

They asked Pakistan to provide information about his arrest, imprisonment and death. Afghan Taliban spokesman Zabihullah Mujahid said Obaidullah was arrested in Balochistan in 2009 and died in a Karachi jail the following year.

Other Pakistani leaders who met Karzai on Saturday included Chaudhry Shujaat Hussain and Mushahid Hussain Syed of the PML-Q, Aftab Ahmed Khan Sherpao of the PPP-S, and Haji Muhammad Adeel, Afrasiyab Khattak and Zahid Khan of the Awami National Party.

Karzai stressed on the exchange of parliamentary and political delegations.

He further stressed the need to set up an independent Pakistan-Afghanistan Jirga as a platform to resolve outstanding issues between the two countries.